Introduction

plot_ly(diamonds, x = ~cut, color = ~clarity, colors = "Accent")

## No trace type specified:
##   Based on info supplied, a 'histogram' trace seems appropriate.
##   Read more about this trace type -> https://plot.ly/r/reference/#histogram

plot_ly(diamonds, x = ~cut)

## No trace type specified:
##   Based on info supplied, a 'histogram' trace seems appropriate.
##   Read more about this trace type -> https://plot.ly/r/reference/#histogram

plot_ly(diamonds, x = ~cut, y = ~clarity)

## No trace type specified:
##   Based on info supplied, a 'histogram2d' trace seems appropriate.
##   Read more about this trace type -> https://plot.ly/r/reference/#histogram2d

plot_ly(diamonds, x = ~cut, color = "black")

## No trace type specified:
##   Based on info supplied, a 'histogram' trace seems appropriate.
##   Read more about this trace type -> https://plot.ly/r/reference/#histogram

## Warning in RColorBrewer::brewer.pal(N, "Set2"): minimal value for n is 3, returning requested palette with 3 different levels

## Warning in RColorBrewer::brewer.pal(N, "Set2"): minimal value for n is 3, returning requested palette with 3 different levels

So color = "black" wouldn’t work

plot_ly(diamonds, x = ~cut, color = I("black"), stroke = I("red"), span = I(2))

## No trace type specified:
##   Based on info supplied, a 'histogram' trace seems appropriate.
##   Read more about this trace type -> https://plot.ly/r/reference/#histogram